Here are some questions from DailyWritingTips.com readers about subject-verb agreement and my responses.
1. In your post concerning subject-verb agreement, why would you use a singular verb for ten liters of water? “Of water” is a prepositional phrase, and the subject is liters. We have always been taught to ignore the prepositional phrase that modifies the subject when determining agreement.
The sentence I used in this post exemplifies an exception to the rule: When the first noun in a “[noun] of [noun]” phrase is a percentage, distance, fraction, or amount, the verb agrees with the second noun.
2. I have a question about noun-verb agreement in conjunction withand. For example, should a sentence read, “There was no moon and no clouds” or “There were no clouds and no moon”?
Either construction is acceptable; the verb form should agree with the form of the nearest noun. However, “There were no clouds and no moon” is better because the plural form of the verb agrees with both clouds and the combination of “clouds and . . . moon,” so it feels more natural.
3. When I write sums, I normally use plus and equals, but if I use andinstead of plus, should I use is, or are, before the sum?
In mathematical equations, when we put two or more numbers through an operation, they are considered a single set. As you note, we use a singular verb — we say or write, for example, “One plus two equals three,” not “One plus two equal three” — so “One plus two is three” is correct.